Smoke pots are typically used as ground-to-ground or ground-to-air signaling devices, target or landing zone marking devices, or as screening devices for military unit movements. Prior art and experimentation teach that obscuration efficiency is a function of particulate size, refractive index and concentration in the atmosphere. Conventional pyrotechnic obscurant compositions are, therefore, based on materials which generate a dense primary particulate, such as inorganic oxides, or compounds which easily form atmospheric aerosols, such as hydrochloric acid, polyphosphates, or phosphoric acid.
Chemicals in the category of screening smokes are those which, when dispersed in air, produce a cloud of finely divided particles of solid, liquid, or both, These are used to shield tactical operations or disrupt the movements of the enemy. Outstanding examples of such materials are: fuel oil used in “artificial fog” generators, white phosphorus, sulfur trioxide, titanium tetrachloride, and so called zinc chloride smokes. Each of the above-listed smoke-generating compositions is characterized by certain advantages and disadvantages in military operations, depending upon the importance of such factors as mobility of the smoke producing apparatus, toxicity, logistical considerations, and the total obscuring power of the composition employed.